Inheritence — Part 1 MCQs with Explanations

Option A: Only if the subclass is marked as "final" This option is incorrect. Marking a subclass as "final" means that it cannot be subclassed further, and it has no impact on the inheritance of constructors. Option B: Yes, a subclass inherits constructors from its superclass This option is incorrect. In Java, a subclass does not inherit constructors from its superclass. However, a subclass can call the constructors of its superclass using the super keyword. Option C: Only if the superclass is marked as "static" This option is incorrect. The "static" keyword cannot be applied to classes or constructors in a way that would affect inheritance. Option D: None of the above This option is correct. In Java, constructors are not inherited by subclasses. Subclasses must explicitly define their own constructors, although they can call their superclass's constructors using the super keyword. Conclusion: In Java, a subclass does not inherit constructors from its superclass, making Option D: None of the above the correct answer.

In Java, protected members (fields and methods) of a superclass are accessible to its subclasses. Unlike private members, which are inaccessible outside the class, protected members can be accessed: 1. Within the same package: Any class within the same package can access protected members. 2. In subclasses (even if in a different package): A subclass can access protected members of its superclass, even if they are in different packages, provided they are accessed through inheritance (i.e., using super or via an instance of the subclass). This ensures that subclasses get access to important superclass members while still maintaining some level of encapsulation.

The given code snippet involves inheritance in Java. It defines two classes: Parent and Child . The Child class extends the Parent class, which means it inherits its fields and methods. Inside the Parent class, there is a private integer variable x with a value of 10. In the Child class, there is another integer variable x with a value of 20. Additionally, the Child class has a display() method that prints the values of super.x and x . In Java, when you access a variable with the super keyword, it refers to the variable of the superclass. When you access a variable without super , it refers to the variable of the current class. Now, let's analyze what happens in the display() method: - super.x refers to the x variable in the Parent class, which is 10. - x refers to the x variable in the Child class, which is 20. So, the display() method will print "10 20" because it first accesses the x variable of the superclass ( Parent ) using super.x and then accesses the x variable of the current class ( Child ) directly. Therefore, the correct answer is: Option B: 10 20

1. new Derived(); statement executes and invoke the non-parametrized constructor of derived class i.e. public Derived(); 2. As Derived class is a subclass of class Base so super(); executes and calls the super class constructor and prints "Base" . 3. After that this("Examveda"); executes and call the parametrized constructor public Derived(String s); of Derived class as this always refer to the current object. So, it prints "Examveda" . 4. Lastly the print statement executes and prints "Derived" Hence output is BaseExamvedaDerived .

It is important to understand that it is the type of reference variable - not the type of the object that it refers to - that which determines what members can be accessed. That is, when a reference to a subclass object is assigned to a super class reference variable, we will have access only to those parts of the object defined by the superclass. In the above program method method3() is defined in the class C which is a subclass of B and so A . Even the reference variable a refers to c , a can't access method3() as this method is unknown to class A .

When object of new derived is called, the flow goes to Derived() first, by default super(); is present in Derived() as the first statement, so the flow now goes to Base. Here value is initialised to 0 and then addValue() is called. The addValue has been overridden in Derived() hence The Base's addValue() will perform value+20(0+20) .After this control flows back to Derived()'s addValue() where again value+20 is done (20+20). Hence Answer is 40

We cannot reduce the visibility of the inherited method from super class. If the overridden or hidden method is public, then the overriding or hiding method must be public; otherwise, a compile-time error occurs. If the overridden or hidden method is protected, then the overriding or hiding method must be protected or public; otherwise, a compile-time error occurs. If the overridden or hidden method has default (package) access, then the overriding or hiding method must not be private; otherwise, a compile-time error occurs.

We can't store super class object in subclass reference But we can store subclass object in super class reference.

Reference variable can refer to any object of the same type as the declared reference OR can refer to any subtype of the declared type. Reference variable "b" is type of class B and reference variable "c" is a type of class C. So Compilation fails.

The process of acquiring properties and behaviors of one class by another is the correct answer to “What is inheritance in Java”. This question is standard in competitive examination syllabi for Inheritence.

extends is the correct answer to “In Java, which keyword is used to implement inheritance between classes”. This question is standard in competitive examination syllabi for Inheritence.

The class that is inherited from is the correct answer to “What is a superclass in Java”. This question is standard in competitive examination syllabi for Inheritence.

To call a method or constructor of the superclass is the correct answer to “What is the "super" keyword used for in Java”. This question is standard in competitive examination syllabi for Inheritence.

No, private members are not visible to subclasses is the correct answer to “In Java, can a subclass access private members (fields and methods) of its superclass”. This question is standard in competitive examination syllabi for Inheritence.

"Extends" is used for class inheritance, while "implements" is used for interface implementation is the correct answer to “What is the difference between "extends" and "implements" in Java”. This question is standard in competitive examination syllabi for Inheritence.

Parent is the correct answer to “What is the result of the following code snippet? class Parent { protected void display() { System.out.println("Parent"); } } class Child extends Parent { void show() { display(); } } public class Main { public static void main(String[] args) { Child obj = new Child(); obj.show(); } }”. This question is standard in competitive examination syllabi for Inheritence.

No, a subclass can only have one superclass is the correct answer to “In Java, can a subclass have more than one superclass”. This question is standard in competitive examination syllabi for Inheritence.

To indicate that a class cannot be further extended is the correct answer to “What is the purpose of the "final" keyword in Java inheritance”. This question is standard in competitive examination syllabi for Inheritence.

No, constructors are not inherited, especially private constructors is the correct answer to “In Java, can a subclass inherit private constructors from its superclass”. This question is standard in competitive examination syllabi for Inheritence.

Redefining a superclass method in a subclass with the same method signature is the correct answer to “What is the concept of method overriding in Java inheritance”. This question is standard in competitive examination syllabi for Inheritence.

Yes, a subclass inherits static methods from its superclass is the correct answer to “In Java, can a subclass inherit static methods from its superclass”. This question is standard in competitive examination syllabi for Inheritence.

ParentChild is the correct answer to “What is the result of the following code snippet? class Parent { void display() { System.out.println("Parent"); } } class Child extends Parent { void display() { super.display(); System.out.println("Child"); } } public class Main { public static void main(String[] args) { Child obj = new Child(); obj.display(); } }”. This question is standard in competitive examination syllabi for Inheritence.

No, package-private members are not accessible to subclasses from different packages is the correct answer to “In Java, can a subclass access package-private members (fields and methods) of its superclass defined in another package”. This question is standard in competitive examination syllabi for Inheritence.

10 20 is the correct answer to “What is the result of the following code snippet? class Parent { int x = 10; } class Child extends Parent { int x = 20; void display() { System.out.println(super.x + " " + x); } } public class Main { public static void main(String[] args) { Child obj = new Child(); obj.display(); } }”. This question is standard in competitive examination syllabi for Inheritence.

Yes, starting from Java 8, a subclass can override default methods from interfaces is the correct answer to “In Java, can a subclass override a default method from its superclass”. This question is standard in competitive examination syllabi for Inheritence.

To allow access to members within the same package and subclasses in any package is the correct answer to “What is the purpose of the "protected" access modifier in Java inheritance”. This question is standard in competitive examination syllabi for Inheritence.

Yes, public members are accessible to subclasses from different packages is the correct answer to “In Java, can a subclass access public members (fields and methods) of its superclass defined in another package”. This question is standard in competitive examination syllabi for Inheritence.

Parent is the correct answer to “What is the result of the following code snippet? class Parent { void display() { System.out.println("Parent"); } } class Child extends Parent { public static void main(String[] args) { Child obj = new Child(); obj.display(); } }”. This question is standard in competitive examination syllabi for Inheritence.

No, static methods cannot be overridden is the correct answer to “In Java, can a subclass override a static method from its superclass”. This question is standard in competitive examination syllabi for Inheritence.

Parent is the correct answer to “What is the result of the following code snippet? class Parent { static void display() { System.out.println("Parent"); } } class Child extends Parent { public static void main(String[] args) { Child obj = new Child(); obj.display(); } }”. This question is standard in competitive examination syllabi for Inheritence.

No, private fields are not inherited by subclasses is the correct answer to “In Java, can a subclass inherit private fields from its superclass”. This question is standard in competitive examination syllabi for Inheritence.

No, final methods cannot be overridden is the correct answer to “In Java, can a subclass override a final method from its superclass”. This question is standard in competitive examination syllabi for Inheritence.

Compilation error is the correct answer to “What is the result of the following code snippet? class Parent { final void display() { System.out.println("Parent"); } } class Child extends Parent { void display() { System.out.println("Child"); } public static void main(String[] args) { Child obj = new Child(); obj.display(); } }”. This question is standard in competitive examination syllabi for Inheritence.

3 and 5 is the correct answer to “Which of the following is true? 1. A class can extend more than one class. 2. A class can extend only one class but many interfaces. 3. An interface can extend many interfaces. 4. An interface can implement many interfaces. 5. A class can extend one class and implement many interfaces.”. This question is standard in competitive examination syllabi for Inheritence.

123 is the correct answer to “What is the output of the following program code? abstract class C1{ public C1(){ System.out.print(1); } } class C2 extends C1{ public C2(){ System.out.print(2); } } class C3 extends C2{ public C3(){ System.out.println(3); } } public class Test{ public static void main(String[] a){ new C3(); } }”. This question is standard in competitive examination syllabi for Inheritence.

(II) and (III) is the correct answer to “The concept of multiple inheritance is implemented in Java by I. Extending two or more classes. II. Extending one class and implementing one or more interfaces. III. Implementing two or more interfaces.”. This question is standard in competitive examination syllabi for Inheritence.

Class Two method1 is the correct answer to “What will be the output? interface A{ public void method1(); } class One implements A{ public void method1(){ System.out.println("Class One method1"); } } class Two extends One{ public void method1(){ System.out.println("Class Two method1"); } } public class Test extends Two{ public static void main(String[] args){ A a = new Two(); a.method1(); } }”. This question is standard in competitive examination syllabi for Inheritence.

prints "Mammal eats food" is the correct answer to “What is the result of compiling and running this program? class Mammal{ void eat(Mammal m){ System.out.println("Mammal eats food"); } } class Cattle extends Mammal{ void eat(Cattle c){ System.out.println("Cattle eats hay"); } } class Horse extends Cattle{ void eat(Horse h){ System.out.println("Horse eats hay"); } } public class Test{ public static void main(String[] args){ Mammal h = new Horse(); Cattle c = new Horse(); c.eat(h); } }”. This question is standard in competitive examination syllabi for Inheritence.

ClassCastException exception is thrown at runtime. is the correct answer to “What will be the result of compiling and executing the following program code? class Vehicle{ public void printSound(){ System.out.print("vehicle"); } } class Car extends Vehicle{ public void printSound(){ System.out.print("car"); } } class Bike extends Vehicle{ public void printSound(){ System.out.print("bike"); } } public class Test{ public static void main(String[] args){ Vehicle v = new Car(); Bike b = (Bike) v; v.printSound(); b.printSound(); } }”. This question is standard in competitive examination syllabi for Inheritence.

a b c is the correct answer to “Determine output: class Small{ public Small(){ System.out.print("a "); } } class Small2 extends Small{ public Small2(){ System.out.print("b "); } } class Small3 extends Small2{ public Small3(){ System.out.print("c "); } } public class Test{ public static void main(String args[]){ new Small3(); } }”. This question is standard in competitive examination syllabi for Inheritence.